FR3077384A1 - METHOD FOR OPERATING A WIRELESS COMMUNICATING ELECTRONIC APPARATUS AND WIRELESS COMMUNICATING ELECTRONIC APPARATUS USING THE SAME - Google Patents

Abstract

This method of operation of a wireless electronic communicating device comprises steps of: a) acquiring (100) a radio frequency frame representative of at least one piece of information intended to be transmitted by the radiofrequency transmitter in a radiofrequency message; b) determining (102) the amount of energy available in the energy reserve; c) determining (104) the length of the radiofrequency message to be transmitted; d) determining (106) transmission parameters of the radio frequency transmitter, as a function of the determined values of the length of the message and the amount of energy available in the energy reserve; e) transmitting (108) the message by the transmitter, using the determined transmission parameters.

Description

Operating method of a wireless communicating electronic device and wireless communicating electronic device implementing this process

The invention relates to a method of operating an electronic device communicating wirelessly. The invention also relates to an electronic device communicating wirelessly implementing this method.

The invention is applicable to the field of home automation systems, and more generally, to the field of wireless communicating objects electrically supplied by an on-board rechargeable energy reserve.

Known communicating objects are electronic devices provided with an on-board radiofrequency transmitter suitable for exchanging data with other remote devices, for example within an “Internet of Things” type network. To communicate with a remote device, these objects transmit a radio frequency message by means of their radio frequency transmitter, which is supplied by the energy reserve.

These devices are typically autonomous in electrical energy, that is to say that they are not connected to an electrical network and depend solely on their internal energy reserve to function. This reserve can be recharged by an energy recovery device built into the device.

In known manner, energy recovery techniques, called "energy harvesting" in English, are used to generate small amounts of electricity from energy sources present in the environment. These sources of energy can be vibrations or movements of a mechanical organ, temperature gradients, electromagnetic radiation such as radio frequency waves, visible light or infrared light, and many other examples.

A major drawback of these known devices is that, due to the very principle of energy recovery techniques, it is not possible to know in advance how much electrical energy has been collected by the device at one time. given instant and in particular before the emission of a radiofrequency message.

For example, it is not possible to predict what the amount of light received by a photovoltaic energy recovery device will be at each instant, or to predict when or with what force a user will press a control button coupled to a piezoelectric energy recovery device.

Consequently, it is not possible to guarantee that the energy reserve will contain, at a given time, a sufficient amount of energy to allow the device to perform certain functions. In particular, there is a risk that, when the device has to transmit a radiofrequency message, the energy reserve does not contain enough electrical energy for the message to be able to be transmitted successfully, i.e. 'it can be issued in its entirety. The operation of the electronic device is therefore not guaranteed in all circumstances, which is not satisfactory.

It is these drawbacks that the invention intends to remedy more particularly, by proposing an electronic device communicating wirelessly in which the energy consumption is optimized when sending a radiofrequency message.

To this end, the invention relates to a method of operating an electronic device communicating wirelessly, the electronic device comprising:

an electronic control circuit comprising a radiofrequency transmitter configured to transmit a radiofrequency message according to a communication protocol and

- a rechargeable electrical energy reserve configured to electrically power the electronic device, the operating method being implemented by the electronic control circuit and comprising steps:

a) acquisition, by the electronic control circuit of the electronic device, of a radiofrequency frame representative of at least one item of information intended to be transmitted by the radiofrequency transmitter in a radiofrequency message;

b) determination, by the control circuit, of the quantity of energy available in the energy reserve;

c) determining, by the control circuit, the length of the radiofrequency message intended to be transmitted, the radiofrequency message comprising at least the acquired radiofrequency frame;

d) determining the emission parameters of the radiofrequency transmitter, the determination being implemented by the control circuit as a function of the determined values of the length of the message and of the amount of energy available in the energy reserve ;

e) transmission of the radiofrequency message by the radiofrequency transmitter, using the determined transmission parameters.

Thanks to the invention, prior to the sending of each message, the operating parameters of the radiofrequency transmitter are automatically adapted as a function of the energy available in the energy reserve.

According to advantageous but not compulsory aspects of the invention, such a process can incorporate one or more of the following characteristics, taken in isolation or according to any technically admissible combination:

- During step b), the amount of available energy is determined from measured values of the amount of energy supplied to the energy reserve by an energy recovery device of the device electronic over time and from measured values of the amount of electrical energy supplied by the energy reserve to the device over time.

- During step b), the determination of the quantity of energy available is estimated:

b1) by measuring a first electrical quantity representative of the quantity of energy available from the energy reserve, preferably a first electrical voltage across the terminals of the energy reserve;

b2) by measuring a second electrical quantity representative of the quantity of energy available from the energy reserve, preferably a second electrical voltage across the terminals of the energy reserve, this measurement being carried out following a withdrawal of a quantity energy preset in the energy reserve;

b3) and calculating the value of the amount of energy available in the energy reserve from the first and second measured values.

- The method comprises, during step b), the measurement of the temperature within the electronic device, by a temperature measurement device, and the correction of the amount of energy available in the reserve of energy as a function of the measured temperature.

- Step d) comprises the selection of a particular operating point from a set of predefined transmitter operating points stored in a computer memory of the control circuit, the set of predefined operating points defining rules for correspondence relating the predefined operating points with, on the one hand, values or ranges of values of message lengths and, on the other hand, with values or ranges of values of quantity of energy available in the energy reserve, and in which the particular operating point is selected by identifying, within the assembly, the predefined operating point corresponding to the determined values of message length and of quantity of available energy.

- Step d) further includes determining a class of operation for the radio frequency transmitter.

- Step d) further comprises determining the energy necessary for the radiofrequency transmitter to transmit a radiofrequency message having the determined length with a predetermined radiated energy.

- The emission parameters include the operating class and the operating point of the transmitter and in which step d) comprises a sub-step for optimizing the operating classes and an operating point of the transmitter as a function of the determined values of the length of the message and of the amount of energy available in the energy reserve.

According to another aspect, the invention also relates to an electronic device communicating wirelessly and comprising an electronic control circuit comprising a radiofrequency transmitter configured to transmit a radiofrequency message according to a communication protocol and a reserve of rechargeable electrical energy configured to supply electrically the electronic device. The control circuit is programmed to implement the operating method as described above.

According to advantageous but not compulsory aspects of the invention, such a device can also incorporate one or more of the following characteristics, taken in isolation or according to any technically admissible combination:

- The device also includes an energy recovery device intended to electrically recharge the energy reserve, and the control circuit is programmed to implement the operating method as described above.

- The electronic device also includes a temperature measuring device intended to measure the temperature inside the device, and the control circuit is programmed to, during step b), correct, depending of the measured temperature, the value of quantity of available energy determined.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the description which follows, of an embodiment of a method and of an electronic device given solely by way of example and made with reference to the accompanying drawings in which:

- Figure 1 is a schematic representation of an electronic device communicating wirelessly according to the invention;

- Figure 2 is a block diagram of an electronic control circuit of the electronic device of Figure 1;

- Figure 3 is a flow chart of an operating method of an electronic device communicating wirelessly according to the invention and intended to be implemented by the device of Figure 1;

- Figure 4 is a flowchart detailing a step in the process of Figure 3 according to one of the embodiments of the invention;

- Figure 5 is a schematic representation of a table of values allowing the choice of emission power values during certain modes of implementation of the method of Figure 3;

- Figure 6 is a schematic representation of a message to be sent by the electronic device of Figure 1 according to certain embodiments of the invention;

- Figures 7 and 8 are flow charts each detailing a step in the process of Figure 3 according to one of the embodiments of the invention.

FIG. 1 represents an electronic device 2 communicating wirelessly, suitable for exchanging data by a radiofrequency link with a remote receiver according to a communication protocol. The device 2 is, for example, intended to be part of a network of communicating objects of the "internet of things" type. In this example, the device 2 can be used within a home automation system, such as a building management system or an alarm system, and can thus communicate via a radio frequency link with other electronic devices. of the network, or even with a central server.

The device 2 comprises a rechargeable electrical energy reserve 4, an energy recovery device 6 and an electronic control circuit 8 comprising a radio frequency transmitter 10. The reference “12” designates a subset of the device 2 allowing implement a main function of the device 2. For example, the sub-assembly 12 is connected to the control circuit 8.

Advantageously, the device 2 comprises a protective box, inside which are housed the control circuit 8, the energy reserve 4, and at least part of the energy recovery device 6 and of the sub-assembly. 12.

According to embodiments of the invention, the device 2 is a device for measuring one or more physical quantities, for example an environmental physical quantity such as a temperature, a humidity rate, a brightness, a rate sunshine, atmospheric pressure, and / or a concentration of at least one chemical element. The device 2 can alternatively be a human presence detector, or a fire detector. In these embodiments, the sub-assembly 12 includes a sensor adapted to deliver a signal representative of the corresponding physical quantity or quantities.

According to other embodiments, the electronic device 2 is a control point, intended to receive instructions from a user and then retransmit these instructions towards another device on the network, for example bound for a control center. According to an alternative embodiment, the control point retransmits the instructions of the user in the direction of an actuator such as a concealment device, a lighting device or any other home automation device.

In these embodiments, the sub-assembly 12 comprises an interface for acquiring at least one command, or man-machine interface, comprising one or more selection elements such as a button and / or a scroll wheel, or a touch screen , or any other actuable control member.

The energy reserve 4, also called “energy reservoir”, has the function of storing the electrical energy necessary for the operation of the device 2. The electrical energy reserve 4 is also configured to supply the device electrically electronics 2 and in particular the electrical control circuit 8. For example, the device 2 is autonomous, that is to say it operates without necessarily being connected to an electrical distribution network.

According to a first example, the energy reserve 4 is a rechargeable electric accumulator battery, for example of lithium-ion technology, or of lithium-polymer technology, or of nickel-metal hydride technology, or of nickelcadmium technology, or of any other appropriate technology.

According to a second example, the energy reserve 4 comprises one or more capacitors, or a battery of super-capacitors.

In general, the energy reserve 4 is a physicochemical storage element.

The energy reserve 4 is here on board the device 2. For example, the energy reserve 4 has a storage capacity less than or equal to 10 Watt.hour.

The energy reserve 4 is electrically connected to the control circuit 8 to supply the latter with electrical energy. According to embodiments, when necessary, the energy reserve 4 is also connected to the subassembly 12, for example, so as to supply it with electrical energy.

The energy recovery device 6, called “energy harvesting” in English, is configured to electrically supply the energy reserve 4, in order to recharge it, from energy collected in the environment of the device. 2.

For example, the energy recovery device 6 is configured to collect electrical energy from solar radiation, electromagnetic radiation, temperature gradients, vibrations or movements of a mechanical organ, or a combination of several ambient energy sources.

Thus, according to an example, the device 6 for recovering energy comprises a photovoltaic solar panel. According to another example, the device 6 comprises a turbine associated with a wind turbine. According to yet another example, the device 6 comprises an electromechanical element, for example a piezoelectric module, configured to transform into electricity displacements undergone by a mechanical member of the device 2 and in particular of the sub-assembly 12.

According to a particular and nonlimiting example of implementation, if the subassembly 12 comprises an acquisition interface provided with one or more selection elements that can be actuated mechanically, then the device 6 for energy recovery can advantageously include a piezoelectric element mechanically coupled to one or more of the selection elements of the acquisition interface. In this way, the actuation of a selection element by a user generates a displacement which is transformed, by the piezoelectric element, into a small amount of electrical energy capable of recharging the energy reserve 4.

FIG. 2 represents an exemplary embodiment of the control circuit 8. In this example, the arrows with double line symbolize power links and the arrows with single line symbolize data exchange links.

The control circuit 8 here comprises the radio frequency transmitter 10, a programmable electronic calculation unit 20, a computer memory 22, an electrical supply circuit 24 and a device 26 configured to determine the quantity of energy available in the reserve d energy 4. Optionally, the electronic circuit 8 can also include a device 28 for measuring the temperature inside the device 2.

The measuring device 26 is adapted to deliver a signal representative of at least one electrical quantity relating to the energy reserve 4, and more particularly an electrical quantity representative of the electrical power delivered by the energy reserve 4. For example , the electrical quantity is the electrical voltage across the energy reserve 4. The measuring device 26 then comprises at least one electrical voltage sensor configured to deliver a signal representative of the voltage across the reserve 4 and / or a sensor configured to deliver a signal representative of the current flowing between the energy reserve 4 and a load electrically connected to at least one terminal of the energy reserve 4. The operation of the measuring device 26 is described in the following.

The device 28 for measuring the temperature comprises at least one temperature probe, such as a thermocouple or a probe with a negative or positive temperature coefficient, for example placed inside the device 2, preferably near or in contact with the reserve 4. As a variant, the device 28 for measuring the temperature can be omitted.

The control circuit 8 here comprises an acquisition interface 30, suitable for collecting measurement signals delivered by the measurement devices 26, 28 and for relaying the corresponding information to the calculation unit 20. For example, the acquisition interface 30 includes an analog-digital converter.

According to embodiments, the control circuit 8 is an integrated circuit of the system on chip type, also called “System on Chip” in English. As a variant, the circuit 8 is an electronic card provided with printed circuits on a dielectric support and on which the components of the control circuit 8 are mounted.

The function of the computing unit 20 is to automatically control the operation of the control circuit 8. For example, the computing unit 20 is a programmable microcontroller, or a microprocessor, preferably with low power consumption. According to one embodiment, the acquisition interface 30 is integrated into the calculation unit 20.

The computing unit 20 is in particular programmed to control the sending of a radiofrequency message to a remote receiver belonging to the communication network. To this end, the unit 20 is programmed to acquire a radiofrequency frame representative of at least one item of information intended to be transmitted according to a communication protocol by the radiofrequency transmitter 10 of the electronic device 2. For example, the radiofrequency frame is generated by the sub-assembly 12, and is representative of a command received and / or of at least one environmental physical quantity. The radio frequency frame can also be representative of an alarm message and / or of a diagnosis relating to the internal state of the electronic device 2.

The calculation unit 20 is also programmed to generate a radio frequency message comprising at least the acquired radio frequency frame. According to an implementation mode, the radiofrequency message can comprise a repetition of the radiofrequency frame acquired for the purpose of redundancy. Advantageously, the repetition of the radiofrequency frame makes it possible to increase the probability that at least one frame is received by the destination receiver.

According to an embodiment, when the message comprises a repetition of identical frames, the successive frames are spaced from each other by a pause of a predetermined length.

In the description, the length of a radiofrequency frame, of a radiofrequency message or of a pause is considered to be equivalent to the duration of transmission respectively of the radiofrequency frame, of the radiofrequency message or of the pause, this at for simplification.

The generated radio frequency message can be sent by the radio frequency transmitter 10 on the initiative of the computing unit 20, or in response to a request received from another device on the network. For example, during the generation of a radio frequency message, the calculation unit 20 performs encoding and / or modulation operations of the information content of the radio frequency frame, according to a predefined communication protocol.

The calculation unit 20 is also programmed to control the operation of the radiofrequency transmitter 10 and of the power supply circuit 24 in order to ensure the transmission of the message over the air, that is to say by means of radiofrequency waves. To this end, the unit 20 is connected to the transmitter 10 by a data link 32 and to a regulating interface of the supply circuit 24 by a data link 34.

The memory 22 is here a non-volatile memory, comprising for example one or more memory modules of Flash technology, or of EEPROM technology, or a magnetic memory, or a phase change memory, or any other appropriate information storage technology. . For example, memory 22 forms a computer-readable, non-transient information storage medium.

The memory 22 contains on-board software and / or executable instructions 40 intended to be executed by the unit 20 to ensure the operation of the electronic control circuit 8, and in particular to control the sending of a radiofrequency message and to activate operates an operating method of an electronic device 2 communicating wirelessly, in particular that described with reference to FIG. 3.

The memory 22 also contains data 42 and a numerical value 44 whose role is described in more detail in the following.

The supply circuit 24 is in particular adapted to electrically supply the radiofrequency transmitter 10 according to a particular operating point. The supply circuit 24 is itself supplied by the energy reserve 4. For example, the supply circuit 24 comprises a power converter, in particular of the continuous type, and advantageously comprises a voltage regulator, such as a linear regulator, electrically connected at the output of the power converter. As an illustrative example, the radiofrequency transmitter 10 can be supplied with an input supply voltage between 0.9 volts and 3.7 volts.

For example, the power converter of the supply circuit 24 is selectively switchable between several operating modes. For example, the power converter can operate either as a voltage step-down (“buck” or “step-down” converter in English), or as a voltage booster (“boost” or “step-up converter”). »In English). The converter can also operate, in each of these operating modes, with an adjustable voltage difference. The voltage difference here designates the amplitude with which the output voltage is raised or, conversely, lowered compared to the input voltage of the converter. The switching and the voltage difference are here controlled by the calculation unit 20.

The transmitter 10 is, for example, a radio frequency interface capable of fulfilling the function of radio frequency transmitter, or of transceiver, although here only the transmission function is described in detail. The transmitter 10 here includes in particular a radiofrequency transmission module, a radiofrequency antenna and a power amplifier, not illustrated. The amplifier is biased by the supply circuit 24 according to a particular operating point. The input of the power amplifier is electrically connected to the output of the transmitter module and the output of the power amplifier is electrically connected to the antenna. The amplifier is configured to amplify the output signal from the transmitting module and feed the radio frequency antenna.

For example, the transmitter 10 is adapted to operate according to a radio frequency communication protocol of the LoRa® type, or of the Sigfox® type, or of the Zigbee® type, or of the WiFi type, or of the LTE type or also of the Bluetooth® Low type. Energy, or any other appropriate radio frequency communication protocol.

The control circuit 8, and more particularly the calculation unit 20, is programmed to optimize the energy consumption of the electronic device 2 during the transmission of a radio frequency message by the transmitter 10 as a function of the amount of energy available in the energy reserve 4. The control circuit 8 is, for example, programmed to implement the operating method described with reference to FIG. 3, in order to prevent the transmission of the message is cut off or interrupted for lack of sufficient energy in reserve 4.

In practice, in this example, the quantity of energy consumed by the control circuit 8, and in particular by the transmitter 10, for transmitting a radiofrequency message of length Lt is noted “Ec” and is given by the following theoretical formula :

E _c = P _s = P _r x - x - x L _t (1) ^K conv ^K RF

In this formula, "Ps >> designates the electric power supplied by the reserve 4 to the supply circuit 24," Pr >> is the power radiated (also called transmission power) by the antenna of the transmitter 10, "R _con v" is the energy efficiency of the supply circuit 24, "R _rf " is the energy efficiency of the amplifier of the transmitter 10. The efficiency R _RF is defined as the ratio of the power Pe supplied at the output by the supply circuit 24 to the amplifier by the power P _r radiated by the antenna. The yield R _conv is defined as being the ratio of the power supplied to circuit 24 by the reserve 4 by the power Pe supplied at the output by the circuit 24. The power Pe supplied at the output by the supply circuit 24 corresponds to the power consumed by the transmitter 8 and in particular by the power amplifier.

When the radiofrequency message is formed by the repetition of several identical frames and of the same length L, the quantity Lt in the above formula is replaced by the product N x L, where “N >> denotes the number of frames of length L .

The length of the message thus determined corresponds to the duration during which the transmitter 10 transmits the radio frequency signal corresponding to the message and therefore the duration during which the transmitter 10 consumes electrical energy.

It is therefore understood that the energy consumed can be modified by playing on the operating parameters of the various elements of the circuit 8 which are involved in sending the message, and more particularly on the operating parameters of the supply circuit 24 and the transmitter 10. These parameters are collectively called “emission parameters” in the following.

In known manner, the emission parameters include in particular the voltages and currents necessary to polarize the power amplifier. These parameters condition in particular the transmission power Pr of the transmitter 10 when the radiofrequency message is transmitted. The emission power Pr depends in particular on the electrical supply current and on the electrical supply voltage supplied by the supply circuit 24 from the energy reserve 4.

Another parameter influencing energy consumption is the operating class of the transmitter amplifier. For example, the operating class of the amplifier directly influences its energy efficiency R _rf . In known manner, the operation of a power amplifier within a radiofrequency transmitter can be characterized by a value called the conduction angle. Amplifiers can thus be classified into several classes according to the value of this conduction angle, such as class A, class AB, class B, class C, class D or even class E. To each class corresponds a value or a range of conduction angle values. These classes are ordered together so that the corresponding conduction angle value decreases from class A to class E. As stated above, the energy efficiency of the power amplifier depends on its operating class; the energy efficiency R _rf increases from class A to class E.

The energy efficiency R _con v of the supply circuit 24 depends on the operating modes of the DC-DC power converter, in particular depending on whether the converter operates as a step-down or step-up device. The energy efficiency R _conv of the supply circuit 24 also depends on the value of the voltage difference between the output voltage and the input voltage of the converter. For example, energy efficiency decreases if the voltage difference increases and vice versa. The yield R _CO n _V is here understood within a range going from 60% to 95%.

The number N of frames transmitted depends on the structure of the radio frequency message. It is common for a message to have identical frames repeated one after the other intended to be transmitted in succession. This redundancy is used to increase the probability that the information content of the message is well received by its recipient in the event of loss of part of the message sent. In this example, to simplify the explanation, we consider here that the message has only one frame of length L.

In the example illustrated, it is considered that the emission parameters liable to be modified during the optimization include all the parameters set out above, although in practice one can only consider some of these emission parameters. .

In general, the optimization of the value of the energy Ec here consists in selecting emission parameters of the transmitter, and more precisely in selecting a set of specific values of each of the emission parameters, for which the value of the energy consumed Ec is lowered below a certain value. As a variant, the optimization may also consist in minimizing a function representative of the energy consumed Ec. It can be a function depending on the energy Ec given by the above theoretical formula and also depending on the temperature of the electronic device 2.

For example, in what follows, a distinction is made, for the emission parameters, on the one hand, the emission class of the amplifier and, on the other hand, the “operating point” of the transmitter 10, the point of operation corresponding to the voltages and currents necessary to polarize the power amplifier of the transmitter 10.

An example of implementation of the operating method of an electronic device communicating wirelessly is now described with reference to FIG. 3. Advantageously, this method allows the dynamic management of the transmission power of a radiofrequency message by an electronic device that communicates wirelessly.

First, during a step 100, a radiofrequency frame representative of at least one item of information intended to be transmitted by the radiofrequency transmitter 10 according to a communication protocol is acquired by the calculation unit 20.

Then, during a step 102, the amount of energy available in the energy reserve 4 is automatically determined. The amount of energy available in the energy reserve 4 corresponds to the amount of energy deliverable by the latter to the electronic device 2 and in particular to the control circuit 8. Step 102 of determining the amount of energy available is implemented by the control circuit 8, for example using the calculation unit 20 and the measuring device 26. The determination of the available energy can be carried out in different ways.

According to a first mode of implementation, the circuit 8 determines, during the operation of the device 2, continuously or at repeated intervals, the amount of energy supplied by the device 6 for recovering energy to the reserve 4. The circuit 8 also determines, continuously or at repeated intervals, the quantity of energy supplied, over time, by the energy reserve 4 to the various elements of the electronic device 2. To do this, the electronic device 2 may include a measurement device electrically connected between the energy recovery device 6 and the energy reserve 4 adapted to measure the energy entering the energy reserve. It can be, for example, a current sensor or a voltage sensor.

In other words, the circuit 8 monitors the quantities of energy entering and leaving the reserve 4, so as to carry out an energy balance of the energy reserve 4. These determinations are made here using the measuring device 26, by measuring at least one electrical quantity, preferably by measuring the voltage across the energy reserve 4 and the current flowing in and out of the energy reserve 4. The corresponding available energy is then calculated automatically, knowing the properties of reserve 4, for example the equivalent resistance. The calculation can be carried out by the calculation unit 20 using a program stored in the memory 22. Likewise, the properties of the energy reserve can be stored in the memory 22.

From a known initial value of energy available at an initial instant in the reserve 4, it is thus possible to know at each subsequent instant what is the quantity of energy available in the reserve 4. For example, this quantity of energy available is recorded in memory 22 as a numerical value 44. This numerical value 44 is updated by the calculation unit 20 throughout the operation of the apparatus 2, either continuously or at time intervals predefined, either each time the reserve 4 is requested to be recharged or to charge energy.

Thus, to know the quantity of energy available in the energy reserve, during step 122, the unit 20 automatically reads the numerical value 44 previously recorded in the memory 22.

As a variant, the quantities of energy entering and leaving the reserve 4 are recorded separately in the memory 22 and the calculation of the energy available in the energy reserve 4 is only carried out during step 102.

According to a second embodiment of step 102, the determination of the quantity of available energy is estimated or extrapolated by carrying out several measurements of an electrical quantity of the reserve 4 by means of the measuring device 26. An example of such a method is illustrated in FIG. 4 and here comprises operations, or sub-steps, numbered 1020 to 1024. This example is described with reference to an electrical voltage across the terminals of the energy reserve 4, but in a variant , other electrical quantities relating to reserve 4 can be used such as current.

Thus, during operation 1020, the no-load voltage across the energy reserve 4 is measured, by means of the measuring device 26. A first voltage value is thus obtained.

By “unladen”, it is understood here that the measurement of the electric voltage across the terminals of the energy reserve 4 is carried out while no electrical load is connected at the output of the energy reserve 4, c that is to say that no electric current is supplied by the reserve 4. This gives a first voltage value. For this, the electronic device 2 may include a switching circuit electrically connected to the output of the energy reserve 4. The switching circuit is configured to switch the output of the energy reserve either on the load, in operation , or on the measuring device 26 during a vacuum measurement. The switching of the switching circuit is controlled by a processor like that of the computing unit 20. With reference to FIG. 1, the load corresponds to the control circuit 8 and to the sub-assembly 12.

Then, during operation 1022, a predefined quantity of energy is taken from the reserve 4, for example, by debiting a quantity of current courantl predefined for a period of time predefined. To do this, as stated above, the electronic device 2 may include a switching circuit electrically connected to the output of the energy reserve 4. The switching circuit is configured to switch the output of the energy reserve 4 to an electric charge of predetermined characteristics during the time ot, so as to subtract the amount of current ôl. This results in a voltage drop across the energy reserve 4. A measurement of the electric voltage across the reserve 4 is carried out, for example, using the measuring device 26, in order to obtain a second voltage value linked to the current discharge. The values of duration Ô and current ôl are preferably chosen according to the storage technology used for the reserve 4. The value of the duration ôt of current draw is chosen as short as possible in order to avoid taking an amount of current ôl too large and thus avoid over-discharging the energy reserve 4. The aim being to calculate a slope, the duration ôt of sampling must be chosen so as to be able to carry out the calculation. It therefore also depends on the measurement device and in particular on the quantum of the analog-digital converter of the acquisition interface 30.

Then, during operation 1024, an estimate of the energy available in the reserve 4 is made from the first and second measured electric voltage values and by means of a predefined formula which, for example, depends on the nature of the reserve 4. According to one embodiment, the estimation is carried out by the calculation unit 20 using executable instructions, for example stored in the memory 22.

This second embodiment is advantageously used in the presence of an energy recovery device 6 supplying energy to the reserve 4 in the form of a short-duration pulse, as is notably the case of the recovery devices. of energy based on piezoelectric elements. Indeed, such energy recovery devices 6 provide a high voltage for a very short time. Therefore, the first mode of implementation does not always give satisfactory results, because it is difficult to measure precisely the amount of energy supplied by the device 6 to the reserve 4 when this quantity of energy is supplied under the form of a short-duration pulse, for example of duration less than 100 ps.

Thus, at the end of the determination step 102, whatever the estimation method used, there is a value representative of the quantity of energy available in the reserve 4. The quantity of energy available is noted “Er” in the following.

Advantageously, during step 102, the quantity of available energy Er determined is automatically corrected as a function of the temperature value measured by the device 28. In fact, in practice, the performance of the device 6 and / or of the reserve 4 energy can depend on their temperature. This is particularly the case for piezoelectric elements and capacitors. For example, during the determination step 102, a measurement of the ambient temperature within the electronic device 2 is carried out, by the temperature measurement device 28 and, after the determination of the quantity of available energy, a correction is made by applying a correction coefficient to the determined amount of energy Er. The correction coefficient is dependent on the value of the measured temperature. The correction is carried out from a predefined correction law and / or from a precalculated table of values. The predefined correction law and / or the precalculated table of values can be stored in memory 22.

This correction as a function of temperature is advantageously applicable to the two modes of implementation of step 102 previously described. In the first embodiment, the temperature correction can be carried out during each of the measurements over time and not only when executing step 102.

Alternatively, no temperature correction is made and the measuring device 28 can be omitted.

Then, during a step 104, the control circuit 8 automatically determines the length of the radio frequency message intended to be transmitted, that is to say that it chooses to build, from the acquired radio frequency frame, a message more or less long radiofrequency depending on the circumstances.

The radiofrequency message comprises at least the radiofrequency frame acquired during step 100.

According to one mode of implementation, the radiofrequency message only includes the acquired radiofrequency frame.

According to an alternative mode of implementation, the message is composed of a repetition of the frame acquired for the purpose of redundancy. Optionally, the successive frames can be separated by a pause of predetermined length. By way of illustration, FIG. 6 represents an example of a radiofrequency message 60 formed of three identical radiofrequency frames 62 each having the same length L, the three successive frames 62 being spaced from each other by a pause 64 of length L _P predetermined.

With reference to FIG. 7, step 104 of determining the length of the radiofrequency message intended to be transmitted may include several sub-steps referenced 1040 to 1044.

During a sub-step 1040, the control circuit 8 and in particular the calculation unit 20 begins by determining the length L of the radiofrequency frame acquired during step 100.

Step 104 includes a sub-step 1042 during which the calculation unit 20 composes the radio frequency message intended to be transmitted by the transmitter 10.

The composition of the radiofrequency message, namely the number of repetitions of the radiofrequency frame 60 acquired in the message may depend on a predetermined criterion relating to the use of the electronic device 2, in particular relating to the theoretical scope of the radiofrequency message 60 .

For example, when the electronic device 2 is intended to send a message 60 with a short range, it is preferable to give priority to the number of frames over the radiated power. The message therefore includes a high number of frames 62. This has the consequence, for a given quantity of available energy, of reducing the transmission power (also called radiated power) of the transmitter compared to the case where the message 60 comprises only a single frame 62. By “ short range ”means a range of less than about 5m. In the case of a home automation application, this could correspond to a range of the order of a room in a building. This scenario can, for example, correspond to a control point configured to transmit instructions to an actuator, such as a concealment device or a lighting device located near the control point, in the same room.

In the case of short-range radio frequency communication, the causes of non-reception of messages 60 by their recipient are mainly due to occasional interference. It is therefore preferable to repeat the frames 62 so that, in the event of such occasional interference, at least one complete frame 62 still has a good chance of being received by the recipient. Lowering the value of the transmission power is, in this specific case, less harmful, insofar as the recipient is not too far away.

We now consider the case of long-range communication. By "long range" is meant a range greater than 5m, typically, a range up to about 20m or even 30m. In the context of an application in the field of home automation, this would represent a range making it possible to encompass all the rooms of a house, even a range extending to the gate or to the exterior fence of the house. In the case of long-range radiofrequency communication, the causes of non-reception of the radiofrequency message 60 by the recipient receiver are mainly due to a lack of radiated power. It is therefore preferable to favor the transmission power to the detriment of the number of repeated frames. The computing unit 20 therefore prefers to concentrate the maximum power on a reduced number of frames rather than transmitting a high number of frames 62 with insufficient power. This would discharge the energy reserve 4 more quickly without guaranteeing that the recipient will correctly receive the message 60.

In other words, in this case, the calculation unit 20 composes a message 60 comprising only a single frame 62. Optionally, the message can include two frames 62.

Of course, other intermediate cases between these two extremes are possible.

According to one embodiment, the electronic device 2 is configured, during its manufacture, to transmit according to a short range or a long range. The calculation unit 20 is therefore programmed to favor the number of frames over power or vice versa depending on the case. In practice, the appropriate program, executable by the calculation unit 20, is stored in the memory 22 according to the case.

According to an alternative embodiment, the electronic device can be “generic” and be able to either transmit at short range or at long range. For this, the apparatus may include a switch programmed to configure the type of transmission from the control unit 8 and in particular from the transmitter 10, either according to a short range or according to a long range.

According to another embodiment, the electronic device 2 can include a particular ergonomics for switching the emission on a short range or a long range. The particular ergonomics can correspond, for example, to a particular action on one or more selection elements.

Step 104 includes a sub-step 1044 during which the calculation unit 20 determines the length of the radio frequency message 60. The length Lt of the message intended to be transmitted can be deduced by multiplying the length of the frame acquired by the number frame repeat.

Then, during a step 106, the unit 20 chooses the emission parameters of the radiofrequency transmitter 10. The emission parameters essentially comprise the operating point of the transmitter 10 and the operating class of the power amplifier. The transmission parameters are determined so that the theoretical quantity of energy Ec which will be consumed by the control circuit 8 when the message is transmitted is less than the determined quantity of energy Er available in the reserve 4. When this is possible, the unit 20 determines transmission parameters in order to minimize the amount of energy that will be consumed during the transmission of the message.

The computing unit 20 determines the operating class of the amplifier as a function of its architecture and the desired radiated power. The operating class is determined in order to avoid problems of distortion of radio frequency signals.

By way of example, the calculation unit 20 cannot systematically use classes D to B, although having good yields, because in this case the distortion of the signals results in a radiofrequency normative non-conformity due to harmonics too high. Depending on the radiated power, the calculation unit 20 chooses the most appropriate operating class so that the harmonics remain below the threshold imposed by the radio frequency standards. For example, at high power, the computing unit 20 will approach class A or AB, while at low power, the harmonics generated being weaker, an operating class B, C, D or even E may be suitable.

According to another embodiment, the determination of the operating class of the transmitter can be carried out as a function of the radiated power using a table of correspondence between the radiated power and the operating class to be used. as described in more detail below.

The operating point of the transmitter is then determined according to the determined operating class. According to a feature of the invention, the operating point of the transmitter is not determined so as to optimize the operation of the amplifier but so as to optimize the use of the energy available to transmit a radiofrequency message according to the desired conditions.

According to a preferred embodiment, the operating point is selected by the unit 20 from a set of predefined operating points, here stored in the memory 22. For example, the data 42 stored in the memory includes such a set predefined operating points, from which the unit 20 can choose a particular operating point, as a function of the values of the quantity of energy available Er and of the length L of the message intended to be transmitted determined during the preceding steps.

For example, the set 42 defines correspondence rules which relate the predefined operating points with, on the one hand, values or ranges of values of message lengths and, on the other hand, with values or ranges of values of the amount of energy available in the energy reserve 4. In other words, to select a particular operating point, the unit 20 identifies, in the set 42, the predefined operating point which corresponds to the value of the quantity Er of available energy determined during step 102 and also corresponding to the length L of the message determined at the end of step 104.

This set 42 of predefined operating points is, for example, calculated beforehand by the manufacturer of the electronic device 2 and then saved at the factory in memory 22 during its manufacture. These predefined operating points are preferably calculated as a function of the characteristics of the various constituents of the circuit 8, such as the technology used for the energy recovery device 6, the storage technology used for the reserve 4, or even also the properties of the supply circuit 24 and transmitter 10.

Thanks to the set 42 of predefined operating points, the calculation unit 20 does not need to carry out calculations for optimizing or minimizing the theoretical quantity of energy consumed Ec, which is advantageous because such calculations require significant computer resources and may require a fairly long calculation time. The selection of a particular operating point from the set 42 of predefined operating points requires less calculation resources and less calculation time than a complete optimization calculation carried out "on the fly" and in real time.

FIG. 5 represents an illustrative example of such a set 42 of predefined operating points. This assembly 42 is here a table 50 or two-dimensional matrix. Alternatively, however, other data structures can be used, such as a database.

The table 50 comprises lines 52 and columns 54. The references E1, E2, E3, and E4 index the columns 54 and correspond to ranges of values which can take the value of available energy Er estimated during step 102 The references L1, L2, L3 and L4 index the lines 52 and designate intervals of message lengths. The references P1, P2, P3, P4, P5 and P6 designate predefined operating points associated with the intersections of rows and columns. Thus, an operating point is associated here with each pair of interval of available energy values and of interval of message lengths.

For example, each operating point P1, P2, P3, P4, P5 and P6 stored in table 50 is a list of values of the various operating parameters considered. As a variant, each operating point P1, P2, P3, P4, P5 and P6 contained in the table 50 is a pointer which designates an area of the memory 22 in which the values of the various operating parameters considered are stored, in the form a list or any other appropriate digital data structure.

The rows 52 and the columns 54 are here indexed by ranges of values but, as a variant, they can be indexed by discrete values, or by any suitable combination of discrete values and intervals.

In this example, to select a particular operating point, the calculation unit 20 automatically searches for the interval E1, E2, E3 or E4 corresponding to the value Er of estimated available energy, and searches for the interval L1, L2 , L3 and L4 corresponding to the estimated message length. The particular operating point selected is the one associated with the two intervals thus identified. For example, if the available energy value Er belongs to the interval E2 and the value of the length L belongs to the interval L3, then the corresponding particular operating point is the point P3. The particular operating point corresponds in particular to the voltages and currents to be applied to the radiofrequency transmitter 10, and in particular to the power amplifier, to allow the emission, with the maximum power, of a radiofrequency message having the estimated length. taking into account the estimated amount of available energy.

According to one embodiment, step 106 of determining the emission parameters may include a sub-step of optimizing the choice of the operating class and the operating point of the transmitter. Optimization can be carried out by the calculation unit using a suitable executable program stored in memory 22.

According to other modes of implementation, the particular operating point is determined by the calculation unit 20 by performing a minimization calculation of the theoretical quantity of energy consumed Ec previously defined, without having recourse to the assembly 42 The assembly 42 can then be omitted.

For example, the unit 20 is programmed to implement operations for calculating the minimization of a function with one or more variables, for example using a digital resolution or optimization model stored in the memory 22. To determine suitable emission parameters, in particular to select an appropriate operating point, the values of the emission parameters are optimized until a combination is found for which the theoretical value of energy consumed Ec is less than the value of available energy Er, or even the combination for which the value Ec is the smallest possible. In other words, the unit 20 calculates the set of emission parameters which make it possible to obtain an amount of energy consumed which is less than the amount of energy Er available estimated.

Advantageously, the optimization calculation is implemented using constraints defined as a function of the technology used for the energy recovery device 6 and / or the energy storage technology used for the reserve of energy 4. These constraints make it possible to restrict the values that some of the emission parameters can take, which makes it possible to simplify the optimization calculation. These constraints are for example predefined by the manufacturer of the electronic device 2 and are advantageously recorded in memory 22.

For example, these constraints are summarized in the table below when the reserve 4 includes capacitors or supercapacitors.

Energy recovery technology Optimized setting Power converter Amplifier class Piezoelectric element Current Step-down with high tension difference Class B or C Photovoltaic module with cells in series Current Step-down with high tension difference Class AB or B Photovoltaic module with cells in parallel Voltage Elevator with low voltage deviation Class AB or B or even C RF wave collection Voltage Elevator with medium to high voltage deviation Class AB or B or even C

The table indicates, for each energy recovery technology used to recharge reserve 4 (first column from the left), the values to be taken by the parameters relating to the operating mode of the power converter (third column), values that the parameters relating to the amplifier of the transmitter 10 can take, and in particular its operating class (last column) and the current or supply voltage parameter which can vary to optimize the power value Pe consumed by the transmitter 10 (second column), it being understood that the other voltage or current parameter has a value which is imposed by the technology used for the device 6 in conjunction with the reserve 4. By way of illustration, in this table the parameters “voltage difference low ”,“ high voltage deviation ”and“ medium voltage deviation ”respectively refer to a deviation of t ension less than about 1V, a voltage difference greater than about 3V and a voltage difference between these two values.

Advantageously, the optimization is carried out by taking into account the value of the temperature measured by the measuring device 28. However, this is not essential and can be omitted when the measuring device 28 is itself omitted.

Thus, at the end of step 106, the calculation unit 20 has values for the transmission parameters of the radiofrequency transmitter guarantee that the entire radiofrequency message is transmitted with the energy available in the energy reserve 4.

Then, during a step 108, the message is sent by the transmitter 10 using the values of the transmission parameters of the radiofrequency transmitter determined previously.

For example, with reference to FIG. 2, the unit 20 transmits to the transmitter 10, via the link 32, the message ready to be transmitted. The computing unit 20 and in particular its microcontroller, controls the supply circuit 24, here by the link 34, so that it supplies the transmitter 10, and in particular the power amplifier, with the voltages and currents necessary for the polarization of the amplifier around the determined operating point. Thus supplied, the transmitter consumes a power Pe, the value of which is defined by the determined operating point. The unit 20 can also control the supply circuit 24 so that the power converter and / or the voltage regulator operates in the operating mode and with the voltage difference defined by the determined operating point. The unit 20 also controls the transmitter 10 so that the amplifier operates with the conduction angle, and therefore with the determined operating class.

Thus, prior to the emission of each radiofrequency message, the emission parameters of the radiofrequency transmitter are automatically adapted according to the energy available in the energy reserve at the time of transmitting the message.

Thus, because over time the length of the message intended to be transmitted can vary and the amount of energy available is never identical, each message is transmitted with different transmission parameters.

It is therefore understood that the invention makes it possible to avoid the transmission of the message being truncated or interrupted because there would not be enough energy available in the reserve 4.

In addition, the invention is relatively simple to implement, in particular in terms of robustness, ease of manufacture on an industrial scale and cost price. Indeed, given the constraints of compactness and miniaturization, low energy consumption, and unit cost weighing on the device 2, it is not always possible to equip the reserve 4 with a device for regulation and monitoring of the “battery management System” type as found on battery packs of certain technologies, because such monitoring devices are too complex and too expensive in view of the application that will be made of it. device 2.

A first advantageous example of implementation of the steps 104 for determining the length of the radio frequency message 60 and for determining 106 the transmission parameters is described in the case of a long-range transmission.

The computation unit determines during a sub-step 1040 the length of the acquired radio frequency frame 60 and then, during a sub step 1042, composes a radio frequency message 60 comprising only one radio frequency frame 62. In in this case, the length L _T of the message is equal to the length L of the radio frequency frame 62.

Then, during step 106, the control unit 8 and in particular the interval unit 20 determines the emission parameters of the radiofrequency transmitter 10.

The emission being of long range, the power is privileged compared to the number of frame. The calculation unit 20 therefore chooses an operating class from classes A or AB depending for example on the type of recharging device 6.

Once the operating class has been determined, the calculation unit searches the memory 22 for the table 50 comprising the set 42 of predefined operating points. Depending on the amount of energy available and the length L _T of the message 60 intended to be sent, the calculation unit selects the operating point to be applied as described above.

If no operating point satisfies the two criteria of available energy and message length, the calculation unit cannot select an operating point and therefore cannot configure the supply circuit. As a result, no radiofrequency message 60 is transmitted.

According to one mode of implementation, when no message 60 is transmitted, the calculation unit commands the emission of an alert signal intended for the user. The alert signal is any signal, insofar as it is perceived by the user and allows the user to understand that no radiofrequency message 60 can be emitted due to insufficient electrical energy available in the reserve. energy 4. The signal may, for example, be a signal emitted by an element internal to the electronic device 2. The alert signal may be a light signal, for example, flashing or lighting for a time predetermined from a light source, such as a light emitting diode or an indicator light, located on the electrical appliance. It can also be a sound signal emitted by a low-consumption sound device such as a piezoelectric sound device.

A second example of the steps 104 for determining the length of the radiofrequency message 60 and for determining the transmission parameters 106 is now described in the case of a short-range transmission.

The calculation unit determines during a sub-step 1040 the length of the acquired radio frequency frame 60.

In this example, the range being short, the radiofrequency message 60 will have to comprise several successive frames 62. According to a first embodiment, in the case of a long-range transmission, the radiofrequency message comprises a predetermined number N _max of radiofrequency frames. For example, N _max equals 3 or 5.

During sub-step 1042 the calculation unit therefore composes a message 60 comprising N _max frames 62 successive, and possibly N _max -1 pauses 64 each separating two consecutive frames, then determines the length of the message 60.

During step 106, the calculation unit 20 determines the emission parameters of the radio frequency transmitter 10.

Since the transmission is short-range, the number of frames is preferred over the transmission power. Since the power is low, the computing unit 20 therefore chooses an operating class from the classes having a high efficiency such as classes C to D for example depending on the type of recharging device 6 present in the electronic device 2.

Once the operating class has been determined, the calculation unit calls up the table 50 comprising the set 42 of predefined operating points stored in the memory 22.

The calculation unit 20 then browses said table 50 in order to find whether an operating point corresponding to the energy available in the energy reserve and to the length of the radiofrequency message 60 to be transmitted exists. If the computing unit finds such an operating point, it selects it and configures the supply circuit to bias the amplifier according to this operating point. If the calculation unit does not find any point corresponding to the available energy and the determined message length, it decrements by one the number of frames N _max contained in the message 60.

If the value of N _max is greater than or equal to 1, the calculation unit 20 again searches in table 50 if an operating point corresponding to the available energy and to the determined message length exists. The calculation unit 20 repeats this operation until finding an operating point satisfying the two criteria of available energy and message length.

As stated previously if an operating point of the table 50 corresponds to the amount of available energy and the message length considered, the calculation unit 20 selects it and configures the supply circuit to bias the amplifier according to this point Operating. Otherwise no message is sent.

According to one mode of implementation, when no operating point has been found in the table and therefore when no radiofrequency message 60 has been transmitted, the calculation unit 20 controls the transmission of a signal alert to the user.

Another embodiment of the operating method is now described.

During a step 100, the calculation unit 20 acquires a radiofrequency frame representative of at least one item of information intended to be transmitted by the radiofrequency transmitter 10 according to a communication protocol. According to an embodiment, the radio frequency frame can be transmitted by the subassembly of the device 2 through a data exchange link

Then, during a step 104, the control circuit 8, and in particular the calculation unit 20, automatically determines the length of the radiofrequency message to be transmitted.

Step 104 of determining the length of the radiofrequency message can include sub-steps 1040 to 1044 similar to those previously described.

During a sub-step 1040, the calculation unit determines the length L of the acquired frame.

Then, during a sub-step 1042, the calculation unit 20 composes the radiofrequency message intended to be transmitted by the transmitter 10. As stated in the embodiment described above, the composition of the message depends on the range desired program. When the message is intended to be sent with a long range, the radio frequency message includes only the acquired radio frequency frame. When the message is intended to be transmitted with a short range, the radiofrequency message comprises a predetermined number N _max of times the acquired radiofrequency frame, Nmax being a non-zero integer. Optionally, each successive frame is separated by a pause of predetermined length. For example, Nmax can be equal to 3.

Finally, during a sub-step 1044, the computation unit 20 determines the length Lt of the radiofrequency message 60. The length Lt of the message intended to be transmitted can be deduced by multiplying the length L of the acquired frame.

During a step 102, the calculation unit determines the amount of energy available in the energy reserve. The determination 102 of the amount of available energy can be carried out as described above

According to another mode of implementation, the determination 102 of the amount of energy can be carried out using a program executable by the calculation unit recorded in the memory 22. The program can for example implement the following mathematical formula:

Er = ((V ₀ -ESR * lc) -Vmin) * lc * Lt (2)

Where: Er represents the amount of energy available;

V _o represents the no-load voltage of the energy reserve;

ESR represents the equivalent series resistance of the energy reserve; le represents the measurement current;

Vmin represents the minimum operating voltage of the transmitter in transmission, that is to say the minimum voltage for operating the transmitter;

Lt represents the length of the radiofrequency message sent;

The value of the equivalent series resistance, also called internal resistance, of the energy reserve 4 can be stored in the memory 22 and called up by the calculation unit. In order to take account of the aging of the energy reserve 4 and therefore of the evolution of the value of the equivalent series resistance, the value of the equivalent series resistance can be recalculated periodically in order to update the value recorded in the memory. 22.

To this end, the electronic device 2 may include a switching circuit electrically connected to the output of the energy reserve 4 and configured to switch the output of the energy reserve either on the control unit or on a circuit. of measurement. The switching circuit can be connected to the microcontroller of the computing unit in order to control the switching and to acquire the equivalent series resistance of the energy reserve periodically. The period for updating the equivalent series resistance is for example 1 month or 2 months.

In order to determine the measurement current Ic, the switching circuit can also be configured to switch the output of the energy reserve 4 to a current sensor. By way of illustration, the current sensor can be a measurement resistor (or “shunt” in English) connected to ground. A measuring device is connected in parallel to the terminals of the measuring resistor and is configured to deliver a voltage proportional to the value of the current passing through the measuring resistor.

This determination method based on knowledge of the equivalent series resistance can be used generally during step 102, independently of the particular mode of implementation of the operating method described here.

Then, during a step 106, the unit 20 determines the emission parameters of the radiofrequency transmitter 10. The step of determining 106 of the emission parameters of the radiofrequency transmitter 10 can include sub-steps 1060 to 1064, as illustrated in Figure 8.

During a sub-step 1060, the calculation unit determines the energy necessary for the radiofrequency transmitter to transmit a radiofrequency message having the length Lt determined with a predetermined radiated energy.

According to a first embodiment, the calculation unit considers a value of radiated energy Emax predetermined, for example, by reading the corresponding value Emax in the memory 22. From the value of the radiated energy, l the calculation unit 20 determines the energy required by the transmitter 10 to radiate such energy. For this, the calculation unit can use an executable program stored in the memory 22.

The program can for example implement the theoretical mathematical formula (1) defined above.

The calculation unit 20 then compares the determined necessary energy with the quantity of available energy. If the quantity of energy available is strictly greater than the energy required, the calculation unit selects the value of radiated energy. The calculation unit can, for example store the value selected in memory 22. If the quantity of available energy is less than the necessary energy, the calculation unit decrements the value of the radiated power by a predetermined quantity Qe then reiterates the calculations until finding a radiated power value strictly less than the amount of energy available.

According to a second alternative embodiment, the calculation unit 20 can fill in a table of values. A first column of this table of values corresponds to the values taken by the energy radiated between two extreme values, for example from a maximum value Emax to a minimum value Emin with a decrement equal to a predetermined quantity Qe. The extreme energy values Emax and Emin, as well as possibly the value of the increment, can be recorded in memory 22. A second column of this table of values corresponds to the values taken by the energy required. For each line, the calculation unit determines the energy necessary for the radiofrequency transmitter 10 to transmit a radiofrequency message having the length Lt determined with the value of radiated energy of the same line. The calculation unit then goes through the second column in order to find the maximum required energy value strictly less than the amount of energy available in the energy reserve. Once the necessary energy value has been found, the calculation unit selects the corresponding radiated energy value. The calculation unit can, for example store the selected value in memory 22.

By way of illustration, the maximum energy values Emax and minimum Emin can be equal to 25 mW and 1 mW respectively. The predetermined quantity Qe may for example be 1 mW. According to another example, Emax = 15dE3m, Emin = 0dBm and Qe = 1 dB.

Once the radiated power has been selected, the calculation unit determines the operating class of the radio frequency transmitter 10 and in particular of the power amplifier during a sub-step 1062.

According to an implementation mode, a table of values is recorded in the memory 22. The table comprises, in a first column, ranges of pre-calculated radiated power values and a second column comprising a list of operating class, for example from class A to class E. Each range of radiated power values corresponds to an operating class. The table of values thus relates a radiated power to an operating class of the transmitter 10. During sub-step 1062, the calculation unit calls up the table of values relating the values of radiated power to the operating classes. The calculation unit 20 then scans the ranges of values of the column corresponding to the radiated power in order to find in which range of values the selected radiated power value lies. The calculation unit then determines the operating class of the transmitter by reading the operating class corresponding to the interval found.

Finally, during a sub-step 1064, the calculation unit determines the operating point of the transmitter 10 as previously stated. Preferably, the determination 1064 of the operating point is carried out from a table 50 comprising a set 42 of predefined operating points, for example, stored in the memory 22.

The operating method then comprises a step 108 of transmitting the radio frequency message 60 with the transmission parameters of the radio frequency transmitter 10 determined.

Although the invention has been described in relation to an electronic device 2 powered by a reserve of rechargeable energy, other embodiments and other modes of implementation can be envisaged with an electronic device powered by a reserve of non-rechargeable energy, such as one or more batteries. To this end, the electronic device 2 can include an energy meter.

The embodiments, the embodiments and the variants envisaged above can be combined with one another to generate new embodiments.

Claims (11)

1. - Method of operating an electronic device (2) communicating wirelessly, the electronic device (2) comprising: an electronic control circuit (8) comprising a radiofrequency transmitter (10) configured to transmit a radiofrequency message according to a communication protocol and - a rechargeable electrical energy reserve (4) configured to electrically supply the electronic device (2), the operating method being implemented by the electronic control circuit (8) and comprising steps: a) acquisition (100), by the electronic control circuit (8) of the electronic device (2), of a radiofrequency frame representative of at least one item of information intended to be transmitted by the radiofrequency transmitter (10 ) in a radio frequency message; b) determining (102), by the control circuit (8), the quantity of energy available in the energy reserve (4); c) determining (104), by the control circuit (8), the length of the radiofrequency message intended to be transmitted, the radiofrequency message comprising at least the acquired radiofrequency frame; d) determining (106) transmission parameters of the radiofrequency transmitter (10), the determination (106) being implemented by the control circuit (8) as a function of the determined values of the length of the message and of the amount of energy available in the energy reserve; e) transmission (108) of the radiofrequency message by the radiofrequency transmitter (10), using the determined transmission parameters. 2, - A method according to claim 1, wherein, during step b), the determination (102) of the amount of energy available is made from measured values of the amount of energy supplied to the reserve d energy by an energy recovery device (6) of the electronic device (2) over time and from measured values of the amount of electrical energy supplied by the energy reserve to the device ( 2) over time. 3. - Method according to claim 1, characterized in that, during step b), the determination (102) of the quantity of energy available is estimated: b1) by measuring (1020) when empty a first electrical quantity representative of the quantity of energy available from the energy reserve (4), preferably a first electrical voltage across the terminals of the energy reserve (4); b2) by measuring (1022) a second electrical quantity representative of the amount of energy available from the energy reserve (4), preferably a second electrical voltage across the energy reserve (4), this measurement being performed following a withdrawal of a predefined amount of energy from the energy reserve (4); b3) and by calculating (1024) the value of the quantity of energy available in the energy reserve (4) from the first and second measured values. 4. - Method according to any one of claims 1 to 3, wherein the method comprises, during step b), the measurement of the temperature within the electronic device (2), by a measuring device temperature (28), and correcting the amount of energy available in the energy reserve (4) as a function of the measured temperature. 5. - Method according to any one of claims 1 to 4, in which, step d) comprises the selection of a particular operating point (P1, P2, P3, P4, P5, P6) from a set ( 42) of predefined transmitter operating points stored in a computer memory (22) of the control circuit (8), the set (42) of predefined operating points defining correspondence rules relating the operating points predefined with, on the one hand, values or ranges of values of message lengths and, on the other hand, with values or ranges of values of quantity of energy available in the energy reserve (4), and wherein, the particular operating point is selected by identifying, within the assembly (42), the predefined operating point corresponding to the determined values of message length and amount of available energy. 6. - Method according to any one of claims 1 to 5, wherein, step d) further comprises determining (1062) an operating class of the radio frequency transmitter (10). 7. - Method according to the preceding claim wherein, step d) further comprises the determination (1060) of the energy required by the radiofrequency transmitter (10) to transmit a radiofrequency message (60) having the length (Lt ) determined with a predetermined radiated energy. 8. - Method according to any one of claims 1 to 7, wherein the transmission parameters include the operating class and the operating point of the transmitter (10) and wherein step d) comprises a sub step of optimizing the operating classes and an operating point of the transmitter (10) as a function of the determined values of the length of the message and of the amount of energy available in the energy reserve. 9. - Electronic device (2) communicating wirelessly characterized in that it comprises: - an electronic control circuit (8) comprising a radiofrequency transmitter (10) configured to transmit a radiofrequency message according to a communication protocol; - a rechargeable electrical energy reserve (4) configured to electrically supply the electronic device (2); and in that the control circuit (8) is programmed to implement the operating method according to one of claims 1 and 4 to 7. 10. - Electronic device (2) according to the preceding claim, wherein the device (2) further comprises an energy recovery device (6) intended to electrically recharge the energy reserve (4), and in that that the control circuit (8) is programmed to implement the operating method according to one of claims 2 or 3. 11. - electronic device (2) according to any one of claims 9 or 10, characterized in that it further comprises a temperature measuring device (28) intended to measure the temperature inside the device (2), and in that the control circuit (8) is programmed to, during step b), correct, as a function of the measured temperature, the value of quantity of available energy determined.